Closure with liner seal vents

ABSTRACT

A plastic closure includes a shell having a base wall with a skirt for securement to a container finish and a lip that extends radially inwardly from the skirt at a position adjacent to and spaced from the base wall. A liner is compression molded in situ against the base wall, and between the base wall and the lip. The lip has a plurality of circumferentially spaced passages that extend through the lip for venting air during compression molding of the liner.

The present invention relates to compression molding sealing linerswithin closure shells, and more particularly to venting the compressionmold cavity to prevent formation of bubbles in the liner.

BACKGROUND AND SUMMARY OF THE INVENTION

Plastic closures for many types of beverage, food, juice, pharmaceuticaland like applications include a plastic shell that has a lip extendingradially inwardly from the closure skirt at a position adjacent to butspaced from the inside surface of the closure shell base wall. A sealingliner is compression molded in situ on the inside surface of the closurebase wall, with the lip cooperating with compression mold tooling toform the mold cavity. U.S. Pat. Nos. 4,984,703 and 6,660,349 illustrateclosures of this type. It has been proposed to provide vent passages inthe liner compression mold tooling to vent air from the mold cavity asthe liner is being molded. However, passages in the liner compressionmold tooling can become clogged or obstructed, preventing properventilation of the mold cavity and leading to entrapment of air bubblesin the liner. This, in turn, undesirably increases the production scraprate and therefore the cost of producing the closures. It is a generalobject of the present invention to provide a closure in which the linercompression mold cavity is vented through the closure shell rather thanthrough the mold tooling, thereby enhancing the venting of air from themold cavity, reducing or eliminating entrapment of air bubbles in theliners, and reducing the closure scrap rate and the cost of production.

A closure shell in accordance with one aspect of the invention includesa base wall with a skirt for securement to a container finish, a lipthat extends radially inwardly from the skirt at a position adjacent tobut spaced from the base wall, and at least one passage that extendsthrough the lip. In the preferred embodiment of the invention, thepassage is in the form of a channel that opens at a radially inner edgeof the lip and at axially spaced surfaces of the lip. The channelpreferably has a radially inwardly facing surface that angles axiallyaway from the base wall and radially inwardly from the skirt. The lippreferably has a surface that faces axially away from the base wall,with at least a portion adjacent to a radially inner edge of the lipthat is flat and perpendicular to the axis of the skirt. The channelpreferably opens at this flat portion of the axially facing lip surface.

A plastic closure in accordance with another aspect of the presentlypreferred embodiment of the invention includes a shell having a basewall with a skirt for securement to a container finish and a lip thatextends radially inwardly from the skirt at a position adjacent to andspaced from the base wall. A liner is compression molded in situ againstthe base wall, and between the base wall and the lip. The lip has aplurality of circumferentially spaced passages that extend through thelip for venting air during compression molding of the liner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objects, features, advantagesand aspects thereof, will best be understood from the followingdescription, the appended claims and the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a package that includes a container anda closure in accordance with one presently preferred embodiment of theinvention;

FIG. 2 is a fragmentary sectional view of the closure in the package ofFIG. 1;

FIG. 3 is a partially sectioned elevational view of the as-moldedclosure shell in the closure of FIGS. 1 and 2;

FIG. 4 is a fragmentary sectional view taken substantially along theline 4-4 in FIG. 3; and

FIG. 5 is a fragmentary schematic diagram that illustrates tooling forcompression molding a liner in the closure shell of FIGS. 3-4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a package 10 as comprising a container 12 of glass orplastic construction and a plastic closure 14 secured to the finish ofcontainer 12. Closure 14 preferably is secured to container 12 by meansof one or more internal threads (or thread segments) on closure 14 inengagement with one or more external threads (or thread segments) on thefinish of container 12.

FIG. 2 illustrates plastic closure 14 in accordance with one presentlypreferred embodiment of the invention as comprising a plastic cap orshell 16 and a plastic liner 18 compression molded in situ within shell16. Shell 16 includes a base wall 20 and a peripheral skirt 22 havingone or more internal threads (or thread segments) 23 (FIG. 3) forsecuring the closure to the finish of container 12 (FIG. 1). Acircumferentially continuous annular lip 24 integrally extends radiallyinwardly from skirt 22 adjacent to but axially spaced from base wall 20.Lip 24 has an interior surface 26—i.e., a facing the opposing interiorsurface of base wall 20—disposed at an acute angle to base wall 20.Specifically, in the preferred embodiment, surface 26 includes a firstconical surface portion 28 adjacent to skirt 22 at a first acute angleto base wall 20, and a second conical surface portion 30 extending fromsurface portion 28 at a second acute angle to base wall 20. An edge 32forms a third surface 34 at a third acute angle to the base wall. Lip 24has a surface 38 that faces axially away from base wall 20. This surface38 preferably includes a first portion 40 adjacent to the radially inneredge of lip 24 that is flat and perpendicular to the axis of closureskirt 22 (i.e.—perpendicular within the tolerances of the shell moldtooling), and a second radially outer portion 42 that is at an angle tothe axis of the closure skirt. In one exemplary embodiment of theinvention for a 38 mm finish, surface portion 28 is at an angle of 45°,surface portion 30 is at an angle of 10°, surface portion 34 is at anangle of 72° and surface portion is 42 is at an angle of 60°, all withrespect to the central axis of skirt 22.

A circumferential array of angularly spaced air vent openings extendthrough lip 24. These air vent openings preferably are in the form ofslots or channels 44 that open at the radially inner edge of lip 24, andat the upper and lower surfaces of lip 24. Channels 44 have a radiallyinwardly facing surface 46 at an angle to the axis of the closure skirt.Surface 46 is a compound surface in the illustrated embodiment, having afirst portion 48 adjacent to skirt 22 at a first angle to the skirtaxis, and a second portion 50 that extends to lip surface 40 at a secondgreater angle to the skirt axis. The angle of surface portion 50controls the depth of the vent and the vent air flow rate. The angle ofsurface portion 48 is for tool design purposes, and could be the same asthe angle of portion 50. Surface portion 48 in the exemplary embodimentof the invention is at an angle of 15.5° to the closure axis, whilesurface portion 50 is at an angle of 27.5°. The upper end of surface 40preferably is at the inside surface of closure skirt 22, while the lowersurface of surface 50 preferably is at the juncture of lip surfaceportions 40 and 42. (Directional words such as “upper” and “lower” areemployed by way of description and not limitation with respect to theupright orientation of the closure and shell illustrated in FIGS. 2-4.Directional words such as “axial” and “radial” are employed by way ofdescription and not limitation with respect to the central axis ofclosure skirt 22 All exemplary dimensions and angles are nominal.) Inthe exemplary embodiment of the invention, there are twelve ventchannels 44 equally spaced around lip 24, with each channel being about0.025 inch wide. Air vent channels 44 preferably are molded into lip 24during injection or compression molding of the closure shell. As analternative, vent channels 44 can be scored or otherwise formed in lip24 in a post-molding operation.

Sealing liner 18 is compression molded in situ against base wall 20, andbetween base wall 20 and lip 24. Liner 18 may be of any suitableconstruction, such as disclosed for example in any one of U.S. Pat. Nos.4,984,703, 5,306,542, 6,371,318, 6,399,170 and 6,660,349. FIG. 5 is aschematic illustration of tooling 60 for compression molding liner 18within shell 16. Such tooling preferably includes a liner tip 62 that isslidably mounted within a sleeve assembly 64. Sleeve assembly 64preferably includes an inner sleeve 66 and an outer sleeve 68 that,together with tip 62 and closure shell 16, form a cavity 70 forcompression molding liner 18. An air vent passage 72 is provided betweensleeves 66,68. The lower face of sleeve 68 (in the orientation of FIG.5) engages lip surface portion 40 and the radially inner edge of lip 24to close cavity 70. Vent channels 44 in lip 24 open to the lower face ofsleeve 68. During molding of liner 18, a charge of liner material isplaced within shell 16 with mold tooling 60 retracted. The mold toolingis then moved into the shell, with sleeves 66, 68 brought into thepositions illustrated in FIG. 5. Liner tip 62 is then moved further intothe shell to compress the charge of liner material and cause the linermaterial to flow outwardly toward the periphery of cavity 70. The airdisplaced by this material flow can vent through channels 44 andradially outwardly around sleeve 68 so as to prevent entrapment of theair as pockets or bubbles within the liner.

There thus have been disclosed a closure shell, a plastic closure, and amethod of making a plastic shell and closure that fully satisfy all ofthe objects and aim previously set forth. The invention has beendisclosed in conjunction with a presently preferred embodiment thereof,and a number of modifications and variations have been discussed. Othermodifications and variations will readily suggest themselves to personsof ordinary skill in the art in view of the foregoing description. Forexample, the principles of the present invention are illustrated inconjunction with a cold soft drink closure having vent slots in thethreads and a tamper band at the edge of the skirt; however, theinvention is by no means limited to closures of this type. The inventionis intended to embrace all such modifications and variations as fallwithin the spirit and broad scope of the appended claims.

1. A closure shell that includes a base wall with a skirt for securementto a container finish, a lip that extends radially inwardly from saidskirt at a position adjacent to and spaced from said base wall, and atleast one passage that extends through said lip.
 2. The closure shellset forth in claim 1 wherein said at least one passage includes aplurality of circumferentially spaced passages.
 3. The closure shell setforth in claim 1 wherein said at least one passage includes at least onechannel that opens at a radially inner edge of said lip and at axiallyspaced surfaces of said lip.
 4. The closure shell set forth in claim 3wherein said at least one channel has a radially inwardly facing surfacethat angles axially away from said base wall and radially inwardly fromsaid skirt.
 5. The closure shell set forth in claim 4 wherein said liphas a surface that faces axially away from said base wall with at leasta portion adjacent to a radially inner edge of said lip that is flat andperpendicular to an axis of said skirt, and wherein said at least onechannel opens at said flat portion of said axially facing surface. 6.The closure shell set forth in claim 4 wherein said at least one channelhas a radially inner end that opens at said flat portion of said axiallyfacing surface and a radially outer end that opens at a radially innersurface of said skirt.
 7. The closure shell set forth in claim 4 whereinsaid at least one channel includes a plurality of circumferentiallyspaced channels.
 8. The plastic closure that includes: a shell having abase wall with a skirt for securement to a container finish and a lipthat extends radially inwardly from said skirt at a position adjacent toand spaced from said base wall, and a liner compression molded in situagainst said base wall, and between said base wall and said lip, saidlip having a plurality of circumferentially spaced passages that extendthrough said lip for venting air during compression molding of saidliner.
 9. The closure set forth in claim 8 wherein said plurality ofcircumferentially spaced passages include a plurality ofcircumferentially spaced channels that open at a radially inner edge ofsaid lip and at axially spaced surfaces of said lip.
 10. The closure setforth in claim 9 wherein said channels have radially inwardly facingsurfaces that angle axially away from said base wall and radiallyinwardly from said skirt.
 11. The closure set forth in claim 10 whereinsaid lip has a surface that faces axially away from said base wall withat least a portion adjacent to a radially inner edge of said lip that isflat and perpendicular to an axis of said skirt, and wherein saidchannels open at said flat portion of said axially facing surface. 12.The closure set forth in claim 10 wherein each of said channels has aradially inner end that opens at said flat portion of said axiallyfacing surface and a radially outer end that opens at a radially innersurface of said skirt.
 13. A method of making a closure that includesthe steps of: (a) providing a shell having a base wall with a skirt forsecurement to a container finish and a lip that extends radiallyinwardly from said skirt at a position adjacent to and spaced from saidbase wall, (b) compression molding a sealing liner against said basewall, and between said base wall and said lip, by (b1) placing linermaterial within said shell, (b2) engaging said lip with a sleeve to forma mold cavity, and (b3) engaging the liner material with a tip to forcethe liner material radially outwardly within said cavity beneath saidsleeve and beneath said lip, and (c) providing a plurality of ventopenings in said lip so that air within said cavity can escape throughsaid vent openings beneath said sleeve.
 14. The method set forth inclaim 13 wherein said vent openings comprise channels that open at aradially inner edge of said lip and at axially spaced surfaces of saidlip.
 15. The method set forth in claim 14 wherein each of said channelshas a radially inwardly facing surface that angles axially away fromsaid base wall and radially inwardly from said skirt.
 16. The method setforth in claim 15 wherein said lip has a surface that faces axially awayfrom said base wall with at least a portion adjacent to a radially inneredge of said lip that is flat and perpendicular to an axis of saidskirt, wherein said channels open at said flat portion of said axiallyfacing surface, and wherein said sleeve engages said axially facing flatsurface in said step (b2).
 17. The method set forth in claim 15 whereinsaid channels have radially outer ends that open at a radially innersurface of said skirt.